Here is a list of tools to keep track of your knitting progress and your knitting projects, low tech to high tech.
The lowest tech way to keep track is to mark directly on the pattern where you are in the pattern and mark the size you are working on, and the yarn and needles you are using. The most complicated part of this method is to make a copy of the pattern so that you are not soiling the original. You will want to keep the pattern with the project (this may seem obvious, but based on the requests I get for patterns and the time I spend looking for patterns for projects of my own it is not unusual for the two to get separated).
A step up is to add a highlighter or highlighter tape to the list above. Use a highlighter to note where you are on the pattern. And highlight all of the places where two things are going on at the same time and again the size you are working on.
A higher tech solution to keeping track are apps for your smart phone or PDA. If you have an Android or iPhone, go to their respective stores and download an app of your choice. iPhone/iPad apps I have used with a lot of success is Knit Counter by Cordless Dog, with this you can keep track of projects, rows-increases-decreases within a project, needles, yarns, etc.
A final super high tech solution is to use an iPad. With the iPad you can store PDF's of your patterns, and then use the highlighter within the PDF program. The program I like the best is Goodreader by good.iware.ltd. Unfortunately, I am not familiar with non-Apple products, so hopefully someone will note in the forum other smartphone or tablet applications for non-apple products.
There are also row counters that attach to your needles or sit next to you. A crowd favorite is to keep a row of M&M's or candy of your choice in a line next to you (two lines if something is happening at the same time), and eat one every time you complete one of the repeats. For example:
Increase one stitch at the beginning of the row four times. (Eat a piece of candy for each increase, out of candy, then you are done increasing!)
If you check Ravelry or other online forums you will see that all knitters have their own preferences.